Oil metering system for rotary compressor

ABSTRACT

An oil metering system for a rotary compressor of the sliding vane type in which a valve assembly continuously meters oil flow into the compressor during its operation and is effective to prohibit oil flow into the compressor during its &#39;&#39;&#39;&#39;off&#39;&#39;&#39;&#39; cycle, thereby preventing reverse rotation of the compressor rotor previously caused by balancing or equalizing of the inlet and outlet pressures internally of the compressor.

United States Patent Harlin Mar. 14, 1972 [54] OIL METERING SYSTEM FOR ROTARY COMPRESSOR [72] Inventor: Lester E. Harlin, York, Pa.

[73] Assignee: Borg-Warner Corporation, Chicago, Ill.

[22] Filed: May 11, 1970 [21 Appl. No.: 36,161 4 [52] US. Cl ..4l8/87, 418/97 [51 Int. Cl ..F01c 21/04, F04c 29/02, F04c 29/04 [58] Field of Search .4l8/84, 87, 93, 96, 97, 9] 418/98, 99

[56] References Cited UNYTED STATES PATENTS 2,634,904 4/1953 Clerc ..4l8/96 2,929,550 3/1960 Sadler ..418/96 X 2,988,267 6/1961 Kosfeld ..4l7/4 [0 3,056,542 10/1962 Galin ..4l8/96 X 3,251,511 5/1966 Lloyd ..222/ l 89 Primary Examiner-Carlton R. Croyle Assistant Examiner.lohn J. Vrablik Attorney-Donald W. Banner, William S. McCurry and John W. Butcher [5 7] ABSTRACT An oil metering system for a rotary compressor of the sliding vane type in which a valve membly continuously meters oil flow into the compressor during its operation and is effective to prohibit oil flow into the compressor during its off" cycle, thereby preventing reverse rotation of the compressor rotor previously caused by balancing or equalizing of the inlet and outlet pressures internally of the compressor.

3 Claims, 4 Drawing Figures Patented March 14, 1972 I N VE N'TO R 15575? E HAPZ/IV BY %4m $445 ATTO R N EV OIL METERING SYSTEM FOR ROTARY COMPRESSOR BACKGROUND AND SUMMARY OF THE INVENTION This invention relates generally to refrigerant compressors and, more particularly, to an improved oil metering system for a rotary sliding vane compressor.

In one type of conventional refrigeration system, refrigerant vapor is delivered from an evaporator to a compressor which compresses the vapor for delivery to a condenser. Accordingly, the inlet to the compressor is at a relatively low pressure and the discharge outlet from the compressor is at a relatively high pressure.

Most rotary vane compressors employ a differential oiling or lubrication system. More particularly, the oil sump is located on the discharge side of the compressor so that the oil pressure is essentially equal to the compressor discharge pressure. The oil sump is connected by an oil passage to the interior of the compressor and empties into the compressor at some point or inlet which is lower in pressure than the oil pressure. Under operating conditions of the refrigeration system, this method of providing lubrication to the rotor, vanes, bearings, and other moving parts of the compressor is satisfactory.

An important problem encountered in such compressors is that, after the compressor has been operated, build up an oil pressure, and then stopped, the oil under high pressure continues to flow until the compressor inlet and discharge pressures are equalized and, in a refrigeration system, the oil will continue to flow until the entire system is equalized and, in many cases, all of the oil will be forced into the evaporator side of the system. As a result, the compressor is slugged with liquid in the refrigerant vapor at start-up of operation, causing increased forces and overloading on all working parts and increased horsepower input. Also, in the refrigeration system, the hot oil and gas mixture, counterflowing in the suction line, increases evaporator temperature and causes a short cycle; and it is highly probable that the hot" oil and gas mixture will cause opening of the thermal expansion valve to produce an additional increase in flow at start-up. A further difficulty occurs as oil flows into the compressor during its off" cycle and causes reverse rotation of the rotor and creates an objectionable noise. In addition, all of the oil is directed onto the oil separator surface at a high flow condition causing inefficient operation of the separator and possible loss of oil in the sump.

The present invention proposes to solve this problem by an oil metering system including a valve assembly attached to the compressor and having a metering valve rotatable by the rotor of the compressor, oil being forced by discharge gas from the oil sump into the valve assembly. When the compressor is operative, a series of radially and circumferentially spaced, rotating ports in the metering valve are each individually and successively aligned with an inlet port in a stationary plate of the assembly to receive oil under discharge gas pressure, so that when an oil-containing port is positioned by the rotating valve to align with an outlet port, spaced from said inlet port, connected to the vane chambers and bearings of the compressor, there is a substantially continuous flow of oil through the valve assembly during compressor operation. When the compressor operation is discontinued, the flow of oil by the discharge pressure from the oil sump into the compressor is terminated by the valve assembly, as the now-stationary metering valve ports are ineffective to deliver oil from the inlet port to the outlet port.

It is therefore a principal object of the invention to provide an improved oil metering system for a rotary compressor which includes means for preventing flow of oil at high pressure into the compressor upon termination of compressor operation.

Another object of the invention is to provide an improved oil metering system for a rotary compressor which incorporates a valve assembly for metering a continuous lubricating oil flow into the compressor during operation of the compressor and preventing oil flow when the compressor is inoperative.

Additional objects and advantages will be apparent from the following detailed description taken in conjunction with the drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a view, with portions broken away and partly in cross section, of a compressor embodying the oil metering valve assembly constructed in accordance with the principles of the present invention:

FIG. 2 is a cross section view taken along the plane of line 2-2 in FIG. 1;

FIG. 3 is a cross section view taken along the plane of line 3-3 ofFlG. 1; and

FIG. 4 is an exploded view in perspective showing the various pans of the valve assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings and, more particularly, to FIG. 1, the compressor having the improved metering valve assembly constructed in accordance with the principles of the present invention comprises a housing A containing the rotor assembly B, and a shell C surrounding the compressor and attached to the front bearing plate providing one part of the housing.

The compressor housing A includes a casing 10 having a cylindrical bore 12 extending therethrough, a from hearing plate 14, and a rear bearing plate 16 all secured together by bolts 17. The rotor assembly B is received within the casing bore 12 and includes a slotted rotor 20 which carries a plurality of substantially radially extending and reciprocating vanes 22. This axis of rotor 20 is offset or eccentrically arranged with respect to the axis of the bore 12 so that the bore, the front bearing plate 14, the rear bearing plate 16, and the rotor 20 cooperate to provide a crescent-shape compression chamber or cavity 24. Rotor 20 is driven by shaft 28 journaled at 30 in the rear bearing plate 16 and also in the front bearing plate 14. The shaft 28 is rotated, in the direction indicated by the arrow, by any suitable means (not shown).

Suction gas from the evaporator (not shown) is admitted to a passage 35 formed in the front bearing plate 14. Both the front bearing plate and the rear bearing plate are provided with generally crescent-shaped recesses 36 (only one of which is shown in FIG. 2) to admit the suction gas into the suction stage of the compressor cavity 24. The recesses are fluidly interconnected by a channel 37 in the casing body 10.

As the rotor is drawn in the direction of the arrow (FIG. 2), the suction gas is trapped between two vanes and carried forward toward the discharge area. On this occurrence, the volume between the adjacent vanes is reduced thereby resulting in a corresponding increase in pressure of the gas. A discharge valve assembly 38 is located in the discharge zone for assuring proper compression of the gases issuing from the outlet or discharge ports 39 and for preventing reverse flow of gases back into the compression chamber. The valve assembly 38 is of the reed type and comprises the valve reed 40 held in place by a valve guard or stop 41. The discharged compressed gases flow into the hermetic shell C and are ultimately delivered to a discharge passage 42 in the casing 10 which leads to a passage (not shown) in the front bearing plate 14 and connected to the condenser (not shown) from fitting 42a.

In order to provide a source of lubricating oil for the various bearing surfaces and other moving parts of the compressor, there is employed a reservoir or sump for a body of oil 43 in the lower portion of the shell C, and located at the discharge side of the compressor so that the oil pressure is essentially equal to the compressor discharge pressure. The pressure of the discharged gases within the shell C is only slightly below the discharge pressure of the compression chamber in housing A. Accordingly, due to high pressure gases within the shell, the oil, separated from the gases, is forced into and up a tube 44 having one end positioned within the sump portion below the normal level of the oil and its other end connected to an oil metering valve assembly D shown in FIGS. 1,3 and 4. For a more complete discussion of the 1, 3 thus far described, reference is made to US. Pat. No. 3,478,957 issued Nov. 18, 1969.

An important feature of the present invention relates to the construction of the oil metering valve assembly D and its adaptation of the valve assembly D to the compressor to control the flow of lubricating oil from the sump and tube 44 into the compressor during its operation and to prevent the flow of oil when the compressor is inoperative. As shown in FIGS. 1, 3 and 4, the valve assembly D comprises a flat, annular metering valve plate 45 having a D-shaped central opening 46 for receiving a complementary shaped end of rotor shaft 28 to couple the plate to the shaft for rotation therewith. The valve plate 45 is positioned within a ring 47 disposed between the rear bearing plate 16 and a cover plate 48, the ring 47 and plate 48 being secured to the rear plate 16 by a plurality of bolts 49 extending through openings 50 in plate 48 and openings 51 in ring 47 and threaded into openings 52 in plate 16. In this arrangement, the valve metering plate 45 is confined between, and has its sides slidingly engaged with, cover plate 48 and rear bearing plate 16, while ring 47 provides a bearing for the plate 45, during rotation of the plate 45.

The tube 44 is connected at its upper end to cover plate 48 and serves as a conduit to convey oil from the sump 43 to an inlet passage or port 53 in cover plate 48. The metering valve plate 45 is provided with a series of passages or pockets 54 radially and circumferentially spaced in the plate 45 about the axis of rotation of the rotor shaft 28. The rear bearing plate 16 is also provided with a main passage or port 55 having branch outlet passages 56 and 57 communicating with one end of the compression chamber 24, branch passage 56 terminating in the open chamber portion between rotor vanes 22 as shown in F IG. 2, and passage 57 termination at a circular area of the rear bearing plate 16 and in which the radially inner ends of vane slots are disposed.

OPERATION The operation of the metering valve assembly will now be described. As the oil sump is located at the discharge side of the compressor, the oil pressure in the sump is substantially equal to the compressor discharge pressure and, accordingly, the oil in the sump will flow through tube 44 and into the inlet passage or port 53 in cover plate 48 and then into an aligned passage 54 in the metering valve plate 45. If the compressor is inoperative, the plate 45 is stationary and oil flow will terminate at this passage 54. However, if the compressor is operating, rotor shaft 28 and plate 45 rotate and, as each passage 54 in plate 45 is individually and successively aligned with the inlet passage 53 in plate 48, the aligned passages 54 in plate 45 will fill with oil to be conveyed by the plate 45 to main outlet passage 55 for flow through the passage 55 and its branches S6 and 57 into the compressor for providing a substantially continuous flow of oil through the valve assembly D to provide lubrication to the rotor, vanes, bearings and other operating parts of the compressor. When the compressors operation is discontinued, the flow of oil, by the discharge pressure in the oil sump, into the compressor is terminated by the valve assembly D as the metering valve plate 45 is stationary blocking and preventing passage of oil in tube 44 into the outlet port 55 in bearing plate 16.

While this invention has been described in connection with a certain specific embodiment thereof, it is to be understood that this is by way of illustration and not by way of limitation, for example, while the metering valve assembly of the present invention is shown as applicable to a rotary vane type compressor; it is believed apparent that the valve assembly is equally adapted for use with rotary piston type compressors. Accordingly, it is intended to cover in the appended claims all such embodiments, as well as modifications of the valve as, sembly, as fall within the scope of the invention.

What is claimed is: l b 1. A compressor comprising a hermetic casing; a reservoir of lubricating oil in the lower portion of said casing; a compressor unit positioned in said casing and including a shell having a cylindrical wall and spaced parallel first and second walls closing the ends of said cylinder, circumferentially spaced gas suction and discharge ports in said cylinder wall; a slotted rotor eccentrically positioned in said cylinder and having a drive shaft journaled in said end walls with one end of said shaft projecting outwardly of said first wall, a plurality of vanes slidably positioned in the slots in the rotor and engaging said cylinder for compressing gas introduced through said suction port and for discharging it through said discharge port at a higher pressure into said casing, a rotary valve including a disc mounted on said projecting shaft end for rotation with said rotor, means defining an annular chamber for said disc and connected to said first end wall; an oil inlet port in said first end wall and communicating with said cylinder and said chamber; a conduit connected to said reservoir and having an outlet port in said chamber for flow of oil under high pressure gas from said reservoir to said chamber, said outlet port being in circumferentially spaced relation to said inlet port in said chamber; said rotary valve disc having a plurality of circumferentially spaced pockets disposed in annular array and adapted to be successively aligned with said outlet port for receiving oil therefrom and to convey the oil to said inlet port during rotation of said disc by said rotor.

2. A compressor comprising a housing having a cylindrical wall and end walls enclosing the cylinder, said walls defining a compression cavity; suction and discharge ports communicating with said compression cavity; means, including a rotor, in said compression cavity for compressing a gaseous fluid introduced through said suction port and for discharging it through said discharge port at a higher pressure; a closed shell enveloping said housing and containing high pressure gas from said discharge port; a reservoir of lubricating oil in the lower portion of said shell; an oil inlet port in one of said end walls; and means for supplying lubricating oil from said reservoir to said oil inlet port including a rotary valve and a conduit connecting said reservoir and said rotary valve, said conduit providing flow of oil by high pressure gas to said rotary valve, said rotary valve controlling the supply of oil from said conduit to said inlet port and effective to direct oil to said inlet port during operation of said rotor and to prevent oil transfer to said inlet port when said rotor is inoperative, said oil inlet port and the outlet of said conduit being circumferentially spaced from each other about the axis of rotation of said rotary valve, said rotary valve being provided with at least one pocket filling with oil from said conduit outlet for delivery to said oil inlet port during operation of said rotor.

3. The compressor defined in claim 2 wherein said rotary valve comprises a disc connected to and rotatable by said rotor and having a plurality of pockets disposed in annular array and adapted to be individually and successively aligned with said conduit outlet for receiving oil therefrom and thereafter aligned with said oil inlet port during rotation of said disc by said rotor to provide for metered flow of oil from said reservoir into said housing. 

1. A compressor comprising a hermetic casing; a reservoir of lubricating oil in the lower portion of said casing; a compressor unit positioned in said casing and including a shell having a cylindrical wall and spaced parallel first and second walls closing the ends of said cylinder, circumferentially spaced gas suction and discharge ports in said cylinder wall; a slotted rotor eccentrically positioned in said cylinder and having a drive shaft journalled in said end walls with one end of said shaft projecting outwardly of said first wall, a plurality of vanes slidably positioned in the slots in the rotor and engaging said cylinder for compressing gas introduced through said suction port and for discharging it through said discharge port at a higher pressure into said casing, a rotary valve including a disc mounted on said projecting shaft end for rotation with said rotor, means defining an annular chamber for said disc and connected to said first end wall; an oil inlet port in said first end wall and communicating with said cylinder and said chamber; a conduit connected to said reservoir and having an outlet port in said chamber for flow of oil under high pressure gas from said reservoir to said chamber, said outlet port being in circumferentially spaced relation to said inlet port in said chamber; said rotary valve disc having a plurality of circumferentially spaced pockets disposed in annular array and adapted to be successively aligned with said outlet port for receiving oil therefrom and to convey the oil to said inlet port during rotation of said disc by said rotor.
 2. A compressor comprising a housing having a cylindrical wall and end walls enclosing the cylinder, said walls defining a compression cavity; suction and discharge ports communicating with said compression cavity; means, including a rotor, in said compression cavity for compressing a gaseous fluid introduced through said suction port and for discharging it through said discharge port at a higher pressure; a closed shell enveloping said housing and containing high pressure gas from said discharge port; a reservoir of lubricating oil in the lower portion of said shell; an oil inlet port in one of said end walls; and means for supplying lubricating oil from said reservoir to said oil inlet port including a rotary valve and a conduit connecting said reservoir and said rotary valve, said conduit providing flow of oil by high pressure gas to said rotary valve, said rotary valve controlling the supply of oil from said conduit to said inlet port and effective to direct oil to said inlet port during operation of said rotor and to prevent oil trAnsfer to said inlet port when said rotor is inoperative, said oil inlet port and the outlet of said conduit being circumferentially spaced from each other about the axis of rotation of said rotary valve, said rotary valve being provided with at least one pocket filling with oil from said conduit outlet for delivery to said oil inlet port during operation of said rotor.
 3. The compressor defined in claim 2 wherein said rotary valve comprises a disc connected to and rotatable by said rotor and having a plurality of pockets disposed in annular array and adapted to be individually and successively aligned with said conduit outlet for receiving oil therefrom and thereafter aligned with said oil inlet port during rotation of said disc by said rotor to provide for metered flow of oil from said reservoir into said housing. 